Methods for fixing cables in vertical cable trays

Cables in vertical cable trays should be secured using appropriate supports, strain relief sections, and bundling techniques to prevent mechanical stress and ensure safe, code-compliant installation.

Key Principles for Vertical Cable Tray Installation

Support and Spacing: Cables in vertical trays must be supported at intervals that prevent undue mechanical strain and sagging. For vertical runs, the spacing of supports is typically based on cable diameter and type, with fire-resistant supports recommended to prevent premature failure in case of fire . For long vertical runs exceeding 32 meters, strain relief sections should be incorporated, often by offsetting the cable by at least two cable diameters per section . For runs over 100 meters, additional tension-relieving measures, such as short horizontal sections of at least 1 meter, are advised . Bundling and Fixing: Cables should be packed in balanced bundles and secured using cable ties or banding at the center to maintain stability and prevent twisting . Ladder-type trays provide convenient anchor points for tying cables, while ventilated troughs offer continuous support for smaller control or instrumentation cables . Rung spacing of 150–230 mm is recommended for instrumentation and control applications to maintain proper cable positioning . Strain Relief and Bends: At points where the cable changes direction, such as vertical-to-horizontal transitions, the internal bend radius must not be less than the minimum bending radius of the cable. Supports should be applied on either side of the bend to prevent stress on the conductors . Strain relief sections help distribute the weight of the cables and reduce stress on terminations. Environmental Considerations: Material selection for cable trays and supports should account for environmental conditions. For corrosive or high-moisture environments, fiberglass-reinforced plastic (FRP) trays are preferred due to their corrosion resistance and non-conductive properties . Covers or solid bottoms may be used to protect cables from dust, debris, or electromagnetic interference . Compliance and Safety: All installations should comply with relevant standards such as BS EN 61537 for cable trays and BS 6946 for channel support systems . Cables should never be used as walkways or for supporting personnel, and all components should be installed as a tested system to ensure safety . By following these guidelines, vertical cable tray installations can maintain mechanical integrity, prevent cable damage, and allow for safe maintenance and future upgrades. Proper planning of support intervals, bundling, and strain relief is essential for long-term reliability.